The present invention relates to a centrifugal vacuum concentrator and more particularly to large capacity concentrator for concentrating or drying large numbers of samples in the same concentrator in a single operation. These samples can be biological, drug, environmental or analogous materials wherein the material to be recovered by drying is suspended or mixed in a liquid.
The invention also relates to a modular rotor assembly which can be assembled from families of modular components involving use of numbers and types of rotors, rotor spacers and vessel holders required for a particular sample drying operation and scale, the modular rotor assembly readily being reconfigurable from a given assembly form to another assembly form wherein different capacity and numbers of rotors, spacer sizes and sample vessels and the holders therefor are used.
Generally where samples of biological or drug materials such as DNA, RNA etc are to be recovered they will be contained in a liquid or solvent vehicle. The liquid sample is in or is placed in a vessel such as a tube, the tube being mounted on a rotor of the rotor of the concentrator. The rotor can mount plural vessels, e.g., fifty or more. In one known concentrator arrangement, tubes are received in bore passages of the rotor located circularly spaced about the rotor, the bore passages being inclined upwardly and radially toward the rotor center so that during rotor high speed rotation, sample xe2x80x9cbumpingxe2x80x9d is inhibited.
The concentrator, e.g., that described in commonly owned U.S. Pat. No. 4,226,669, is closed to seal the vacuum drying chamber, the rotor is started up and brought up to the required high speed, and the vacuum pump is turned on to evacuate the drying chamber and maintain a prescribed condition of vacuum therein. Under such conditions vaporization of the liquid in which the sample material is contained proceeds and continues until the liquid is fully vaporized and the sample material dried. Heat such as from lamps in the drying chamber can be supplied to facilitate drying.
There has developed a need to process very large numbers of samples such as drug discovery samples. In some research facilities, it is known to have to screen many thousands of samples each month. To meet the demand this creates for high capacity concentrator capability, a vacuum centrifugal concentrator has become available wherein two or three rotors are provided, the rotors being superposed one above another. Further, various forms and capacities of sample vessel holders can be used on the rotors to increase the numbers of sample vessels useable in a single drying operation.
A drawback of these known high capacity concentrators is the difficulty of accessibility to the rotors for loading and unloading of sample vessels. The rotors are situated in a housing wherein space between the rotors and the containment housing inside wall surfaces is limited. In one known concentrator, access to the scientist/technician for loading and unloading operation is from above the rotor. This is not especially disadvantageous as to the circumstance of there being only one large rotor used but if a second below rotor was used, it would be tedious and difficult to have to work around and under an upper rotor when loading or unloading a rotor beneath.
In another known concentrator, plural rotors are housed in a rectangular casing. One side of the casing is provided with a casing height door so that alongside access is available to each rotor. But this access is only as to part of the rotor periphery. To access rotor locations remote from the door, the rotors have to be hand rotated to bring the remote part to the access side of the housing.
The confined chamber space character of these known concentrators also makes them less than satisfactory in regard to servicing components of the concentrator within the chamber such as heaters and in respect of cleaning the interior of the concentrator. An additional and significant consideration is the possibility of a scientist/technician injuring a hand when manipulating same in the chamber in association with the tasks noted above.
A shortcoming of known high capacity concentrators is that same are purpose built in regard to the numbers and constructions of rotors that are used therewith and, while to a lesser extent, the types, numbers and arrangements of vessel holders on the rotors. In other words, it is not possible with the known types to have a character of interchangeabilty allowing altering a concentrator capacity need by adding or removing rotors or using rotors of different configurations especially as such configurations lend to most efficient arrangement of certain ones of vessel holders than others.
Accordingly, it is an object of the invention to provide a centrifugal vacuum concentrator which overcomes the drawbacks of the prior art.
It is a further object of the invention to provide a centrifugal vacuum concentrator with a capacity for drying large numbers of samples in a single operation.
Another object is to provide a centrifugal vacuum concentrator which has the flexibility for drying samples mounted in sample vessels of diverse construction and sample capacity.
A further object is to provide a centrifugal vacuum concentrator which is constructed such that access for loading and unloading sample vessels on the rotors is optimized in that such access is available from all of four quadrants of an imaginary circle whose center is on the rotor axis insuring that quick simple loading/unloading tasking is possible.
Another object is to provide a centrifugal vacuum concentrator which allows clear easy unobstructed access to the space about the rotor assembly for cleaning and maintenance purposes as well as the inner part of the concentrator cover which is elevated clear of the rotor assembly when in open position, this thereby making cleaning, maintenance and other tasks easily and safely carried out.
A still further object is to provide a vacuum centrifugal concentrator modular rotor assembly which is comprised of interchangeable rotors, rotor spacers and sample vessel holders selected from families of such components which thereby allows simple and quick alteration of concentrator capacity for drying samples dependent on types and quantities of the samples which are to be dried.
Another object is to provide a modular rotor assembly for a centrifugal vacuum concentrator which can be pre-assembled and stored at a location proximal the concentrator for quick simple installation when a concentrator drying capacity requirement must be changed on shift over from one protocol of drying to another different protocol involving different numbers and sizes of samples being dried.
Briefly stated, there is provided a large capacity centrifugal vacuum concentrator which includes a rotor assembly mounting a plurality of vertical spaced rotors mounted on a drive shaft and intervened with spacers between each lower rotor and a rotor next above. The rotors and spacers have interengaging drive transmission means for transmitting drive to the rotors and spacers from the drive shaft when it is driven in rotation. The rotor assembly is enclosed by a cover, e.g., a cylindrical stainless steel vessel which sits on a base and with the base, defines a vacuum chamber. When the cover is elevated to an open position, four quadrant access is available for loading and unloading of samples on the rotors. The rotor assembly is made up of interchangeable rotors, spacers and vessel holder frames which are selected from families of such components dependent on particular vessel capacity and holder frame requirements.
In accordance with these and other objects of the invention, there is provided a centrifugal vacuum concentrator for concentrating liquid samples contained in sample vessels comprising a base on which a rotor assembly is mounted. The rotor assembly includes a drive shaft upright and rotatable on the base about a fixed axis, and a plurality of rotors is on the drive shaft spaced one above another each at a corresponding one of a plurality of locations above the base, Each rotor carries sample vessel holding structure. A cover is received on the base, the cover having a closed position wherein it surroundingly encloses the rotor assembly and defines with the base an operating chamber. The cover in closed position thereof engages with the base such as to establish an air excluding seal of the operating chamber with respect to an outside air environment. The cover has an open position wherein the cover is disengaged from the base and unobstructedly located relative to the base such that alongside at rotor level access is user available from locations in each of four quadrants of an imaginary circle the center of which lies on said fixed axis for mounting and demounting sample vessels from the rotor sample vessel holding structure. Means is provided for communicating the operating chamber with a source of vacuum.
The access to the sample holder structure from all quadrants when the cover is open is in a circular course of at least about 330 degrees.
An elevator unit, e.g., a lead screw drive unit, can be used to raise and lower the cover between closed and open positions, such unit being effective to elevate the cover to an open position wherein the cover lowermost part is above a topmost rotor in the assembly.
Means are provided to communicate the chamber with a source of vacuum. The vacuum source can be a vacuum pump housed in the base. Communication of the chamber with the vacuum pump can be by way of an opening in the base communicating with a pump inlet.
A fitting can be located in a head of the cover and be communicated to a fume hood and fume removal operation by a flexible hose to allow removal of noxious and harmful vapors emitted during sample drying and before the cover is opened with lab personnel in the proximity.
Heaters such as tubular heaters encircling an outer periphery of the cover wall can be provided on the cover to heat the chamber, these being mounted vertically spaced on the cover so as to supply heat energy into the chamber in a manner as promotes uniform heat condition in the chamber. Further, one or more lamp heaters can be mounted on the cover wall structure and on a head of the cover to direct heat energy at the rotor levels where the samples are located to promote drying of same. Further a heater can be provided in the base.
Drive means for rotating the drive shaft can be located in the base. The rotors are loosely received on the drive shaft and each lower rotor in the assembly is intervened by a spacer also loosely received on the drive shaft. The spacers set the spacing on the drive shaft between the several rotors mounted thereon. Coupling structure on the rotors is cooperative with coupling structure on the spacers for driving coupling these components to the drive shaft for rotation therewith. This coupling structure can be projections on one of the spacers and rotors and passages or openings in the other of said spacers and rotor in which the projections engage. The drive means can have a drive output with which the lowermost rotor engages with coupling structure, e.g., as aforesaid to effect the transmission of rotary drive to the rotor assembly through the lowermost rotor.
The sample vessel holding structure on each rotor comprises one or more holding frames which can be selected from a family of holding frames of differing holding capacity removably fixable to the rotor. The holding frames receive and hold one or more vessel holders in which sample vessels inclusive of vials, tubes, etc are received.
The invention provides that a lower end of the drive shaft is supported on the base, while the upper end is removably received in a self-centering bearing assembly carried at the underside of the head. This upper end of the drive shaft freely inserts into and removes from the bearing when the cover is closed and opened, respectively.
It is provided that the spacers in the rotor assembly are of a common length set of such selected from a family of differing common length sets. By employing selected ones of the sets, the spacing between rotors is altered and a more or less number of rotors will be in the assembly. In these circumstances, the heights of vessel holders and containers received therein can correspondingly be altered to fit rotor spacing and access requirements.
Use of a family of spacers as well as different configurations of rotors provides an interchangeabilty capability to the rotor assembly for changing the capacity of the concentrator to suit a particular requirement within a spectrum of less rotors with use of large size vessel holders and large capacity sample vessels to a use of more rotors with use of small capacity vessel holder such as stacked microtitre plates.
Other features of the invention provide that a variable speed drive motor can be used, and viewing windows be present in both the cover and outer casing so that a strobe light device mounted at convenient location on the cover head can be projected onto sample vessels so that volume level of samples can be monitored. The strobe light also can be used for checking rotor speed.
According to a feature of the invention, there is further provided a modular structured rotor assembly for mounting to a drive unit of a centrifugal concentrator. This rotor assembly comprises a drive shaft, and a plurality of rotors loosely received on the drive shaft and spaced along the shaft at a succession of rotor locations. Tubular spacers loosely received on the shaft intervene a face of a rotor in the succession and an opposed face of a rotor next following in the succession with each of opposed ones of spacer ends in contact with said face and opposed face. Means are provided for holding the rotors and spacers in urged together relationship on the drive shaft as a longitudinal assemblage. Coupling means are provided for unitarily coupling together each spacer and rotor to the drive shaft for effecting rotation of said spacers and rotors in unison with the drive shaft.
The modular structured rotor assembly is configured to be removably received in a base drive unit in driving relationship with a rotary output member of such unit.
The tubular spacers can be a set of common length spacers selected from a family of differing common length sets of spacers. The selected spacer length sets the spacing between rotors in the succession and the rotors can be color coded differently for each common length set to facilitate assembly.
With a modular structured rotor assembly, it is possible to pre-configure a number of rotor assemblies each intended for a specific capacity and drying sample requirement. Since the rotor assembly components for each specific requirement already are set up, it remains only to lift the unwanted rotor assembly from the base and substitute that needed.
The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements.